Showing papers in "Icarus in 1994"

TL;DR: In this paper, the authors developed and tested a new computer code to follow the long-term dynamical evolution of a swarm of test particles in the solar system and found that the Tisserand parameter, T, does not vary substantially for most comets.

TL;DR: The probability distribution for impact velocities between two given asteroids is wide, non-Gaussian, and often contains spikes according to a new method of analysis in which each possible orbital geometry for collision is weighted according to its probability.

TL;DR: In this paper, the full-disk albedo spectra of the jovian planets and Titan were derived from observations at the European Southern Observatory (ESO) in July 1993.

TL;DR: Good agreement between models and observations of CO, O2, O3, and the escape flux of atomic hydrogen can be achieved, using only gas-phase chemistry, by varying the recommended rate constants for the reactions CO + OH and OH + HO2 within their specified uncertainties.

TL;DR: In this paper, a new numerical tool based on the smooth particle hydrodynamics (SPH) method is proposed for modeling impacts and collisions involving small solid objects. But the model is not suitable for the study of strength-dominated interactions between solid bodies.

TL;DR: In this article, new and updated chemical kinetic data, elemental abundances, and thermodynamic data are used for thermochemical equilibrium and, where relevant, thermochemical kinetic calculations of gas abundances and condensate stability in the hot, deep atmospheres of Jupiter and Saturn.

TL;DR: In this paper, the general problem of satellite and particle dynamics about a uniformly rotating triaxial ellipsoid with constant density is formulated and a table of parameters and classifications for a few known asteroids and comets are given.

TL;DR: In this article, the authors examined the effects of the loss of Mars atmospheric constituents by solar-wind-induced sputtering and by photochemical escape during the past 3.8 billion years.

TL;DR: Milani and Kneževic as discussed by the authors proposed an improved version of the iterative analytical algorithm, resulting in significantly improved accuracy for most asteroids in the low to moderate inclination and eccentricity region of the main belt.

TL;DR: In this article, the authors re-examine the results of the Viking Biology Experiments and conclude that the best model for the martian soil contains oxidants produced by heterogeneous chemical reactions with a photochemically produced atmospheric oxidant.

TL;DR: Titan tholin is largely insoluble in the putative hydrocarbon lakes or oceans on Titan, but can yield the H2O-soluble species investigated here upon contact with transient (e.g., impact-generated) liquid water.

TL;DR: In this paper, carbon dioxide, nitrogen, and nonradiogenic and radiogenic noble gases are tracked from primordial inventories to their present states in a revised model of atmospheric evolution on Mars.

TL;DR: In this paper, a method employing a ratio between reflectances within and outside of the 1 micrometer Fe(2+) crystal field absorption band was developed for remotely identifying highland soils that have reached a steady-state maturity.

TL;DR: In this paper, an empirical algorithm for predicting the presence of water of hydration in the surface material of a solar system body using photometry obtained through the Eight-Color Asteroid Survey (ECAS) filters was developed and applied to the ECAS photometry of asteroids and outer planet satellites.

TL;DR: In this paper, the authors investigated the potential source region for lunar and martian meteorites by integrating physical modeling constraints, geochemical cosmic-ray exposure (CRE) constraints, and petrologic constraints.

TL;DR: In this article, a radiative-thermal conduction model for the vertical thermal structure of Io's atmosphere is developed with solar heating by SO2 absorption in UV and near-IR bands and non-local thermodynamic equilibrium (LTE) cooling by SO 2 nu(sub 1), nu( sub 2), nu (sub 3), vibrational bands and rotational lines.

TL;DR: In this article, a detailed thermophysical and radiative transfer model based on a lunar analogy is proposed to constrain the microwave opacity at each wavelength by modeling diurnal brightness variations over the resolved disk and find that Mercury's regolith is at least two to three times more transparent than the lunar maria and at least 40% more transparent compared to the lunar highlands.

TL;DR: In this paper, an analytical solution has been obtained for the steady-state size distribution of a self-similar collisional fragmentation cascade, which corresponds to a power law for the differential mass distribution, where the exponent α is very nearly 11/6, equivalent to a differential radius distribution dn = C * r -3.5 dr.

TL;DR: In this article, a new model that emphasizes the importance of cohesive forces within the refractory material of cometary nuclei is introduced to explain the prevailing inactivity of nuclear surfaces.

TL;DR: A simple description of the disruption and deceleration of 100-m- to 5-km-diameter comets striking Jupiter is combined with numerical simulations of the subsequent explosions to predict the fate of Comet Shoemaker-Levy 9.

TL;DR: In this article, the location and stability of the five Lagrangian equilibrium points in the planar, circular restricted three-body problem are investigated when the third body is acted on by a variety of drag forces.

TL;DR: Galileo images of Gaspra have been used to determine a main-belt asteroid's photometric properties accurately by providing surface-resolved coverage over a wide range of incidence and emission angles and by extending the phase angle coverage to phases not observable from Earth as mentioned in this paper.

TL;DR: A coupled problem of diffusion and condensation is solved for the H2SO4-H2O system in Venus' cloud layer and a reasonable explanation of the OCS and CO profiles in the lower atmosphere measured by Pollack et al. 1993 is provided.

TL;DR: In this article, a combination of theory, observations of T T Tauri stars, and global conservation laws are presented. The models describe the motions of nebular gas, mixing of interstellar material during the formation of the nebula, and evolution of thermal structure in terms of several characteristic parameters.

TL;DR: A coupled soil/atmosphere transport model for H2O2 on Mars found that the atmospheric concentration is only weakly coupled with soil loss processes, and it was found that organic compounds, protected from an oxidizing environment, may still exist.

TL;DR: In this article, a shoulder near 0.63 micrometers is attributed to oxidized iron in phyllosilicates found predominantly in C- and G-class asteroids reflectance spectra.

TL;DR: In this paper, the authors used the most recent available opacity data to estimate the Rosseland opacities for density and temperature conditions relevant to the fluid molecular envelope of the giant planets and for the compositions inferred from atmospheric measurements.

TL;DR: Gaspra's shape is defined in part by extensive flat areas and large, shallow concavities up to 10 km wide, and one of the flat areas is about 6 km across, and defines a plane within ± 0.2 km as mentioned in this paper.

TL;DR: In this paper, the chemistry of hydrocarbon ions in the jovian ionosphere was modeled, and it was shown that a layer of hydrocarbons is formed in the altitude range 300-400 km above the ammonia cloud top, due largely to direct ionization of H2 absorption lines in the 912- to 1100-A region that penetrate to below the methane homopause.

TL;DR: In this article, three dual-frequency ingress radio occultation experiments were conducted at Venus during consecutive orbits of the Magellan spacecraft, with a solar zenith angle of 108 degrees, reaching below 35 km at 3.6 cm, and below 34 km at 13 cm.